I learned a neat trick on another forum a couple of days ago. If you add a little bit of rubbing alcohol to your soapy water solution when looking for leaks, it will increase the soapiness and be more likely to show the leak. I guess it has something to do with the surface tension of the mixture? I don't KNOW how it works and am not a chemist nor a physicist. LMAO

 

At least you are a mechanic

 

^^^^ LMAO! Good one, buddy.

 

Adding alcohol can extend the life of your soap bubbles and make the lather a lot thicker. Adding isopropyl alcohol to your mixture will extend the suds that your soap makes. For a rich, creamy lather, add isopropyl alcohol to your oil mixture at 1-3% of the total oil weight. Ethanol has the same effect.

It probably lowers the surface tension of the bubbles so that they do not pop as quickly and therefore more exist at any given point in time than would otherwise exist without the isopropyl added.

Still don't know if all that schooling paid off.

The more technical writing I do, but the more snooty I become at everything I read. Especially for my co-workers. No I don't say anything most of the time but I'm amazed at how far certain people have gotten up in the company executive levels that write like 8th graders. Nothing against 8th graders and I do account for the fact that some people have learning disabilities, but I can tell the difference.

 

I finally got the time to track the leak.
the soapy water didn't show me anything, then i even tried smoke and no results.
so i unplugged the line with the green cap, on the firewall side going down, and it made some sucking noise and the purge solenoid did create some vacuum, but nothing happened when i removed the hose.
i took the other end off, the side toward the radiator, and the vehicle started running rough.
does that indicate the purge solenoid is bad and not the hose?

 

How did your mechanic fish it? Code only? Smoke test?

The purge solenoid, when not doing evap readiness testing, is purging the fuel system of captured fuel vapors. The babe stays closed until a certain pressure is reached at which time a solenoid opens the valve and lets the vapors into somewhere near the throttle body. So one connection to the valve is from the canister output, the other connection is the output of the valve running back towards the intake for the vapors to get burned.

If you took off the line from the canister to the valve and nothing happened, then the valve may be stuck closed or mostly closed because you stated you did hear some vacuum. When you removed the other line from the purge valve, you exposed the path that the vapor would take to atmospheric pressure. Basically you created a big vacuum leak and since that air going into the intake is unmetered, you were forcing the engine to run lean.

This is a guess.

Also remember that even if the valve is defective, you may still have a leak somewhere in the system

 

mechanic said he did a smoke test, but when i did it i got nada.
i think i am just going to have to save up a couple hundred bucks and drop it on the gm dealer to find.
want to find out how to tell if the solenoid is functioning.